The tire size on the programmer won't be exact because one guy might be running 80 psi in his tires while the other is running 38, if ya know what I mean. It's called squish factor, or bulge factor.

 

Gotcha, thanks for the info! After the first time doing this, it's easy to do now so i'm not worried about adjusting it.

 

So I was just thinking. I guess technically if my speedometer is correct, my odometer should be correct as well? This morning on my way into work, I reset my trip to test it out and averaged like 20.7 mpg driving 65-67 MPH with my 33.9" tires.

Too good to be true? I guess I can try to hand calculate it when my tank is gone.

 

Correct.

My lifetime average at just over 6000 km's is 13.9 liters/100 km's which equals 16.9xx mpg, so say 17 mpg with 34.6" tires. A lot of this is dependent on how you drive of course but a lot of mine is spent in morning traffic.

My current tank is running about 18-19 mpg but I've gotten much better. One trip I took to Long Point and back which is about an hour and 15 each way I got 11.5 liters/100 km which is just over 20 mpg. That included one long wait in a drive through at Tim Hortons and some construction zones in Port Dover., but that's also averaging around 55 mph, which is premium for good mileage. It's definitely doable!

 

I have brand new (as in yesterday) Toyo 295/60/20 tires, I used the Hypertech programmer and set to 32.25, I would say the digital readout speedometer is about 1/2 of a Kilometre Per Hour Fast, with these being new tires the readout will get a little faster than actual speed as the tires wear down a bit, and I guess at that point one could to use 32.5 setting. However its close enough for me for now.

Tony2

 

Looking to program mine this weekend with the hypertech. Does anybody have an idea of good starting point for 33 inch tires? (275/60/20)

 

I just calibrated mine today. I went from OEM 30.6" tires to 32.1" tires and stock it read 3MPH slow, so I set it to 32". Well, it was 3MPH fast then, so I went to 31.25". It was 1MPH fast, so I bumped it down to 31" where it's now 0-1MPH fast.

 

Huh, surprising I'm paying $170 for it and it's that far off. I'm going from 31.89 up to 33.23 and I have no GPS to compare against. Any suggestions from folks?

 

You could always use your phone with an app. That's what I'm doing, using a navigation app on my iPhone.

 

Yeah I was wondering if I could do that, started looking for apps after I posted that message.